Barnacles, which include the sea acorn, are remarkable in many ways and do not look like crayfish.
In adulthood, they lead a sedentary lifestyle, attaching to all kinds of underwater objects - rocks, stones, piles, ship bottoms. The body of barnacles is enclosed in a hard calcareous house, consisting of individual plates. Some of these plates are movably interconnected, so the crustacean can push the plates apart and, from time to time, push the pectoral legs into the resulting gap, making characteristic swings. At the same time, water with planktonic organisms is driven inside the house. This is how you eat and breathe.
The presence of a hard shell and a sedentary lifestyle for a long time forced scientists to attribute these animals to the type of molluscs. Only by discovering the larva of barnacles, similar in structure to other crustaceans, scientists found out that these animals belong to the class of crustaceans.
Where do sea acorns live?
“You will live your life for now, a lot of all sorts of dirty shells stick to our sides” - Mayakovsky used such a metaphor, comparing human life with the life of the ship. Indeed, imagine that a newly built ship leaves the harbor and begins sailing. The speed of its course is known, it is quite within the schedule. However, every day the movement is slowing down. More and more time and fuel are spent on overcoming the same route. Why is this happening? The bottom of the ship is overgrown with various marine animals, forming powerful layers, as a result, friction against the water increases, and the speed drops.
The basis of fouling of ships is made up of barnacles - sea acorns.
They settle not only on ships. They are strewn with coastal rocks and stones, they attach themselves to mollusk shells, to crab shells, settle on the skin of whales, on a whalebone and even on the teeth of sperm whales, on the sides of fish and other most incredible objects that are under water. Sea acorns look like a small white cup, consisting of several "petals". Inside the calyx, a cone of several valves is visible, shaped like a tooth. The flaps of this tooth are able to open, and the legs of the crustacean protrude through the hole formed.
At the bottom of such a house, securely closed with very hard doors, the crustacean itself lies on its back. The front of his head is bent under the body in such a way that the antennae are in the middle of the "sole". The back of the head is enlarged, so the acorn's mouth is turned upwards. The crustacean, protruding legs covered with long bristles from the house, straightens them like a fan, and then folds them. These movements create a current of water directed inside the house. The food of sea acorns is quite diverse due to the fact that the legs are covered with bristles of different density: they sit more often on the front legs, and less often on the hind legs. As a result, different legs filter out particles different sizes. Sea acorns eat algae, bacteria, and many other small planktonic creatures, primarily their relatives, the copepods. They also swallow their own larvae, but the adult larvae of sea acorns are not digested by their parents, but come out unharmed.
Since the crustacean is all adult life spends inside the house, he does not need well-developed sense organs, but something remains of them. Sea acorns are able to distinguish light from darkness with a single primitive eye. Of course, the crustaceans do not care at all what it is now - day or night, and they did not have a peephole for this at all. With its help, acorns react to an instantaneous change in illumination, i.e. they notice a shadow falling on their shell, and in fact it may be from a predator. Just in case, they quickly retract their legs and close the doors of the house. If the acorn shell is shaded at a constant frequency for a long time, the crustacean stops responding to this stimulus, it gets used to the fact that the shadow does not indicate danger. Among sea acorns there are species in which addiction occurs at different intervals. The more “fearful” crustaceans do not “believe” for a very long time that they are not in danger, while the more “daring” ones quickly get used to not reacting to shading. In nature, sea acorns orient their houses so that the entrance to it is directed towards the light. In case of unsuccessful settling of the larva, the crustacean is able at the very beginning of its sedentary life slightly rotate the house so that the light falls directly into its “window”. This, however, is not limited to the requirements of sea acorns when choosing the position of the house. They try to place their dwelling in such a way that the entrance is directed towards the currents. Then the constant flow of water brings more food particles. Some acorns are so “lazy” that they stop swinging their legs altogether to drive water into the sink, and sit motionless, hanging their bristly legs like a net, towards the current.
Reproduction of the sea acorn
Most species of sea acorns are bisexual organisms, but self-fertilization is not common in them. Crayfish manage to mate without leaving home, with one individual acting as a male and the other as a female. Such marriages are possible only in settlements where acorn houses are closely adjacent to each other. The copulatory organ of sea acorns is very long and is able to reach the neighboring house to transfer sperm there. crustaceans living in all alone capable of self-fertilization. Fertilized eggs are dressed in a common chitinous shell and stored in the cavity of the house.
Sea acorns spend their early childhood in much the same way as their relatives - other crayfish. After hatching from the egg, the larva leads a free lifestyle, molts several times and turns into a larva with a bivalve shell. It is always ajar, and the legs of the crustacean stick out of it, with the help of which it swims. After some time, the larva settles and settles on permanent residence, attaching to the substrate with front short antennae. Reliability of attachment is ensured by the adhesive secretion of the cement glands. The larva sheds its temporary bivalve shell and begins to build a reliable, durable home around itself.
How much does a sea acorn balyanus cost (average price for 1)?
Sea acorn Balanus or Balanus belongs to the genus Crustaceans. A feature of this type of sea acorns is an almost immobile lifestyle. The sea acorn balyanus is attached to a hard, most often rocky surface. Own original name sea acorns or balyanuses were obtained due to the characteristic shape of the shell of barnacles, which resembles the shell of the nut of the same name.
Translated from Latin the species name balanus sounds like an acorn. modern science About 60 species of sea acorns are known. In addition to the officially established scientific name sea acorns balyanus are called sea ducks, tulips or truffles. Sea acorns are also known as persebes or pollicipes.
Due to the presence of shells, sea ducks are often mistakenly referred to as mollusks. If adult individuals of balanus lead a motionless lifestyle, young crustaceans live freely in the thickness of sea water. Nai large quantity diversified different types sea acorns are common in seas located in tropical, temperate and subtropical climates.
Balyanus crustaceans are attached not only to rocky surfaces, but also to the bottoms of ships, as well as to other inhabitants. sea depths like whales or crabs. The basis of the diet of the sea duck Balanus is plankton. It is noteworthy that this species crustaceans can safely survive without food for about a month.
The sea acorn balyanus has been used for culinary purposes since time immemorial. AT industrial scale sea ducks are harvested off the coast of Spain, as well as Portugal and Morocco. In cooking, large individuals of balanus are used, which reach 20 cm in length. Such a rather exotic type of seafood for our latitudes is especially popular and in demand in countries with access to the sea.
Most often, sea acorns are boiled and used in the process of making fish and seafood soups. In addition, crustacean meat can be part of the so-called sea cocktail. Excellent taste characteristics has baked sea duck meat. Seafood professionals and connoisseurs claim that the taste of balanus meat combines the characteristics of shrimp as well as lobster.
In the Mediterranean region, balanuses are eaten in fresh, which means that the seafood has not been pre-cooked. From the core of the shell, tender meat of crustaceans is extracted, which is eaten with sauce from olive oil and vinegar.
It is worth noting that the cost of sea acorns balyanus makes it possible to classify these seafood as delicacies. Balyanus is called sea truffles for a reason. Often the cost of one kilogram of freshly caught crustaceans reaches 400 Euros.
Calorie content of sea acorn balyanus 80 kcal
The energy value of the sea acorn balyanus (The ratio of proteins, fats, carbohydrates - bzhu):
: 0 g. (~0 kcal)
: 0.1 g (~1 kcal)
: 0 g. (~0 kcal)
Energy ratio (b|g|y): 0%|1%|0%
Among the most famous and, probably, better than the rest of the crustaceans hiding from the human eye are barnacles , or sea acorns (Cirripedia).
They are the only ones of all their relatives who lead a motionless lifestyle. They are usually attached to rocks, shells, coral and ship bottoms. When too many sea acorns gather on the bottom, this interferes with the course of the ship, it loses speed.
Although acorns prefer to settle in shallow water and in the tidal zone, it happens that they attach themselves even to whales and big fish. Motionless, protected by a multi-lamellar shell consisting of calcium carbonate, sea acorns hide in it and freeze at low tide. But once again in the water, the crustacean looks out of the shell, sticking out six pairs of long legs, with a wave of which it filters the water, trapping food particles - microorganisms. Its legs sway rhythmically, attracting plankton. The sea acorn does not have gills, and its legs also absorb oxygen from the water. The single eye of this crustacean is probably only able to distinguish between light and dark.
Sea acorns can often be seen on rocks and rocks at low tide. In addition, they settle on large marine animals - such as this gray whale.
The sea acorn belongs to barnacles. These creatures are unique in many ways, as they don't look like crayfish in appearance.
Mature individuals lead a sedentary life, attaching to a variety of underwater objects - stones, rocks and ship bottoms.
The body of the sea acorn is protected by a hard calcareous house, which consists of individual plates. A certain part of the plates are movably connected to each other, so the sea acorn can push them apart and stick the pectoral legs into the resulting gap, performing characteristic swings with them. At this point, water, along with planktonic organisms, penetrates into the house. So the sea acorn breathes and eats.
Because sea acorns have a hard shell and are sedentary, scientists have long classified them as mollusks.
It wasn't until acorn larvae were discovered that appeared similar to crustaceans that scientists realized that sea acorns belonged to the crustacean class.
Where do sea acorns live?
A huge number of shells and crustaceans are attached to the bottoms of ships. new ship swims at a certain speed, but over time it slows down. As a result, it takes more time to overcome the old routes. What is it connected with? The bottom of the ship is covered huge amount a variety of marine animals, so whole layers are formed. This leads to the fact that the friction against the water increases, and the speed indicators decrease. Among the various marine animals attached to sea vessels, most of which are barnacles, namely sea acorns.
These crustaceans settle not only on ships, they stick around coastal stones and rocks, attach to the shells of crabs, mollusks, whales, fish and various subjects that fall into the water. They can live on whalebone and even on the teeth of sperm whales. In shape, sea acorns are similar to small white cups, consisting of several petals. The cone is formed from several wings. This cone is shaped like a tooth. The sea acorn can open its valves and protrude its legs through the holes.
The crustacean itself lives at the bottom of its "acorn". At the bottom of the house, formed from closed solid doors, there is the crustacean itself. In the sea acorn, the head is bent under the body so that the antennae are located in the middle of the "sole". The mouth of the crustacean is turned upwards, and rear end head is enlarged. The sea acorn sticks its legs through the cracks, opens them with a fan, and then folds them. Thanks to such movements, a current of water is created that penetrates into the house.
The diet of these crustaceans is quite diverse. This is due to the fact that the legs of the sea acorn are covered with bristles of different density: on the back they are more rare than on the front, as a result, the legs filter particles of different sizes. Sea acorns feed on bacteria, algae, and various planktonic creatures. Most the diet consists of the closest relatives - copepods. In addition, sea acorns feed on their own larvae, but adult larvae are not digested, but come out intact.
"Colonies" of sea acorns are very numerous. Since sea acorns spend their entire adult life inside the house, they do not need well-developed sense organs. But these crustaceans, nevertheless, have certain feelings, for example, they can distinguish darkness from light with the help of a single primitive eye. Crustaceans do not need to determine the time of day, the peephole serves a completely different purpose. The eye helps the crustacean to determine the instantaneous change in illumination, that is, to understand that a shadow is falling on the shell, which may also be from a predator. When the light changes, the sea acorn instantly retracts its legs and tightly closes the doors of the house.
If you regularly shade the sea acorn, then over time it will stop responding to this, as it will understand that it is not in danger. Habituation in different types of sea acorns occurs at different time intervals. More wary species take longer to believe they are not in danger, while others are much quicker to ignore shading. These crustaceans always orient their house so that the entrance to the house is located towards the light. If the larva of the sea acorn unsuccessfully sat on the seabed, the crustacean at the beginning of its sedentary life can slightly turn it around so that the entrance is located towards the light.
For sea acorns, it is important not only the location of the house to the light. They also try to attach themselves to a marine object so that the entrance is directed towards the current, in which case the water current will bring more food particles. Some individuals are so lazy that they completely stop moving their legs, do not drive water into the sink, but hang their legs against the current, like a net, and sit motionless.
The sea acorn begins to build its "house" from the larval stage. Reproduction of the sea acorn
Most of the species of these crustaceans are bisexual organisms, but self-fertilization in these creatures is rare. Sea acorns manage to mate without leaving the house. Such reproduction between sea acorns is possible only if the crustaceans settle next to each other. These crustaceans have a very long copulatory organ, so an acorn can reach them to a neighboring house and inject sperm into it. If the sea acorn lives all alone, it can fertilize itself. The eggs are in a single chitinous shell and are contained in the cavity of the house.
Sea acorns are relatives of the crossfish and other crustaceans.
They lead an attached lifestyle and filter food from the water with the help of feathered jointed limbs.
Appearance
In diameter, the crustacean does not exceed three cm, the shell consists of 4-6 calcareous plates (depending on the species), which in young individuals are colored in White color. Over time, the shell of a marine inhabitant is overgrown with grayish algae.
These marine organisms who live in clear waters and in an open area, the shells are high, and those living in protected areas are flatter.
The shell valves are held and controlled by strong muscles. When the muscles contract, the limbs are hidden in the shell valves, and the hole in the shell is closed.
During low tide, the animal tightly closes the shell valves. The limbs are long, whip-like legs that force water with food particles into the shell. When the tide occurs, the crustaceans are immersed in water, they open a hole in the shell and stick out their legs.
Habitat
Sea acorns live on rocky sea coasts almost all over the world.
Lifestyle
In appearance, marine animals look like mollusks, however, despite the deceptive appearance, they belong to the order "Crustaceans". Inside his dwelling, with the dorsal side down, there is a crustacean similar to a cross.
The thoracic section of crustaceans has six pairs of biramous legs. With their help, animals get. To do this, at low tide, they stick them out of the house, straighten them like a fan and make characteristic waves with them. At the moment of the olive, the crustacean closes all four valves, so it is protected from drying out even when the shell is exposed to wind or sun.
The shell of a marine crustacean consists of four or six calcareous plates. The shells of young crustaceans are colored in light color, however, with age, their color changes, becoming grayish-yellow.
This is due to the fact that the surface of the shell is overgrown with microscopic algae. sheer cliffs cliffs at first glance completely lifeless, but they are inhabited sea acorns. The rocks are located in the tidal zone, literally dotted with them. On many coasts marine inhabitants form a continuous, clearly visible from a distance white stripe.
Food
Adults lead an attached lifestyle, so they cannot engage in active search food. In many ways, their diet depends on what the waters of the tide bring to them. At the moment when the water covers the acorns with their heads, the crustaceans try to open the valves of the shells and stick out their limbs.
They try to quickly swing them in the water, forcing water into the cavity of the house, and eat edible particles that have entered their body along with water.
Modified legs make up to 40 strokes per minute, driving water into particles suspended in it into the cavity of the house. They can also only feed when sea water is washing over them. Therefore, individuals that settled further from the coast feed better than their counterparts, who prefer the tidal zone, where they remain on the surface for a certain time.
Sea crustaceans, constantly washed by water, grow faster, but they do not live long.
reproduction
Sea acorns are hermaphrodites, that is, each individual has female and male genital organs. However, two neighboring living individuals participate in fertilization. Single acorns are barren.
Animals of this species transfer sperm to their partner through a long tube, and fertilized eggs are stored in the mantle cavity for several months. During this time, floating larvae, called nauplii, develop from the eggs. Eggs develop in the womb of a marine organism for 4 months, and then larvae appear from them.
The exit of larvae from the mantle cavity does not depend on the water temperature and calendar dates, but on the time when in large numbers microscopic algae develop - the main food of nauplii.
During the month they swim with plankton carried by sea currents. During this period, the larva molts six times and reaches the stage of a cypris-shaped larva with a bivalve shell. At this stage of development, they do not eat, they are carried by the current for some time, and once in good conditions, settle to the bottom and are attached to the substrate with the help of antennas. Sea acorn larvae settle in dense clumps
Related species
The detachment of barnacles, like the detachment of copepods related to them, belongs to the class of crustaceans.
Lifespan
This type of marine organism wild nature lives no more than 4 years.
conservation status
The sea acorn is very sensitive to pollution. sea waters. Heavy metals accumulate in his body, mainly: lead, so their presence or absence in this region is an accurate indicator of environmental pollution.
- These marine animals settle on any hard surface, so they can often be found on ships, shells sea turtles, clam shells, crab backs and even on starfish, brittle stars and whales.
- Most of these marine organisms become prey for trumpeters. Trumpeters also hunt mussels.
- Sea acorns settle in large colonies, one square meter underwater part of the rock, you can find up to forty-five thousand individuals of these barnacles.
- The shape of their houses is determined by the degree of density of their settlement and some other factors.
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